In the movie The Jerk, Steve Martin’s character writes a letter to his mother saying he learned what his “special purpose” was for after having sex for the first time. Presumably, that was the way she explained his penis to him. This must be a reference to that.
Now is definitely the time to share one of my least useful bits of random knowledge, which is that (this IS related) Nicole Kidman was in a movie in the early 80s called BMX BANDITS.
This looks like the late 80s (or maybe early 90s) and what looks like a freestyle BMX bike with the caption "how to be awesome" - but no mention of Haro or Diamondback? I call bullshit.